One such device is described in British Pat. No. 708,191, and in French Pat. No. 1,588,485.
Rotating the wheel through a certain angle puts the spring under tension, thereby storing energy for subsequent use in operating the circuit breaker.
A restraining member holds the wheel in its fixed position when the spring is under tension.
Generally, an electromagnet is used to act on the restraining member when the circuit breaker is operated in order to release the wheel. One or more force multiplying stages may be interposed between the restraining member and the electromagnet. This makes it possible to use a small electromagnet actuated by a low control current.
The retaining member and the force-multiplying stage(s) are mechanical parts which are difficult and costly to develop and/or adjust.
With increasing values of the currents to be interrupted by circuit breakers, it is necessary to use circuit breakers having mechanical controls of increasing power, and thus requiring springs which are more powerful or more numerous.
The force exerted by the wheel on the restraining system is therefore increased, and as a result more force is required to release the wheel.
An aim of the present invention is to provide an actuator device which, while providing increased operating energy, is nevertheless capable of using the same retaining members, force-multiplying stages, and electromagnets as used by lower power actuator devices.
This problem is not solved in the above-cited documents.